This invention relates to vehicle safety arrangements for protecting occupants of vehicles in the event of a collision.
Conventional vehicle airbags are activated in response to signals produced by a collision detector at the start of a collision. For example, an acceleration or deceleration sensor may be used, or a contact sensor may be provided on the outside of the vehicle containing several contact bars which are normally spaced at a defined distance from each other but are moved into contact with each other upon collision-initiated deformation.
One difficulty encountered in conventional airbag arrangements results from their being designed to protect a vehicle occupant positioned in a predetermined location in the vehicle such as the center of the vehicle seat. At the moment of a collision and the resulting activation of the airbag, however, the occupant may in fact be located in a different position. In the case of an airbag positioned at one side of the occupant and especially serving for lateral protection of the head and chest region of the occupant, the desired protection may not be provided if the occupant's head and chest region are not located in the normal position, i.e., the center of the corresponding vehicle seat, at the time of the collision, but the occupant's head instead is located, for example, close to the lateral airbag. Then, if this airbag is fully activated immediately in a collision, undesirable force may be applied to the occupant by the airbag because of the very small initial distance between the airbag and the occupant.
For this reason, the airbag systems disclosed, for example, in German Patent No. 38 09 074 and German Offenlegungsschrift No. 40 19 677, are at first inflated relatively weakly so that the impact of the bag on a vehicle occupant sitting "out of position" will not be excessive and the airbags are then fully activated. But, in these arrangements, there is a danger that some of the deceleration distance for the vehicle occupant may be lost.
German Offenlegungsschrift No. 40 23 109 discloses an occupant protection system for vehicles in which the sitting position of the occupant in relation to the associated occupant protection device is continuously monitored and the system then controls the timing and extent of the protective measures to be instituted in a collision. Apart from the relatively great cost ultimately required by this system for each vehicle occupant or for each seat in the vehicle, this protection arrangement operates according to the particular "out of position" status of the occupant rather than being designed for the normal occupant position.